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Investigation on a cylindrical ultrasonic micromotor

ZHU Hua, CHEN Chao, ZHAO Chunsheng

《机械工程前沿（英文）》 2007年第2卷第4期页码 394-398 doi: 10.1007/s11465-007-0068-9

摘要： The relationship between the arrangement of ceramics and the force coefficient shows that the maximum excitation efficiency will be obtained when the ceramics are placed at the trough of the first bending mode of the stator. Therefore, a cylindrical ultrasonic micromotor with a novel stator is proposed. The prototype motor is 5 mm in diameter, 30 mm in length and 4.2 g in weight. The micromotor operates with the first bending mode at 53 kHz. Its maximum speed is 350 r/min when the drive voltage is 200 V and the stall torque reaches 2.5 mN · m. As this motor is suitable for miniaturization because of its simple structure, another cylindrical ultrasonic micromotor is developed. Piezoelectric ceramic tube is used as its stator. This micromtor is 2 mm in diameter, 7 mm in length and 0.258 g in weight. Its speed reaches 813 r/min when the drive voltage is 60 V at 75 kHz. The operation mechanism, structure and design method of these two motors are introduced.

关键词： coefficient bending kHz suitable weight

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Low intensity ultrasound stimulates biological activity of aerobic activated sludge

LIU Hong, YAN Yixin, WANG Wenyan, YU Yongyong

《环境科学与工程前沿（英文）》 2007年第1卷第1期页码 67-72 doi: 10.1007/s11783-007-0013-5

摘要： This work aims to explore a procedure to improve biological wastewater treatment efficiency using low intensity ultrasound. The aerobic activated sludge from a municipal wastewater treatment plant was used as the experimental material. Oxygen uptake rate (OUR) of the activated sludge (AS) was determined to indicate the changes of AS activity stimulated by ultrasound at 35 kHz for 0 40 min with ultrasonic intensities of 0 1.2 W/cm. The highest OUR was observed at the ultrasonic intensity of 0.3 W/cm and an irradiation period of 10 min; more than 15% increase was achieved immediately after sonication. More significantly, the AS activity stimulated by ultrasound could last 24 h after sonication, and the AS activity achieved its peak value within 8 h after sonication, or nearly 100% higher than the initial level after sonication. Therefore, to improve the wastewater treatment efficiency of bioreactors, ultrasound with an intensity of 0.3 W/cm could be employed to irradiate a part of the AS in the bioreactor for 10 min every 8 h.

关键词： sonication irradiation kHz treatment efficiency AS activity

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Design of a piezoelectric transducer cylindrical phase modulator for simulating acoustic emission signals

HE Cunfu, HANG Lijun, WU Bin

《机械工程前沿（英文）》 2007年第2卷第3期页码 370-373 doi: 10.1007/s11465-007-0065-z

摘要： To conveniently carry out the pipeline leak experiment in a laboratory, leak acoustic signals are simulated by using the converse piezoelectric effect of a piezoelectric transducer (PZT) cylindrical phase modulator. On the basis of the piezoelectric equations and electromechanical equivalence principle, the transfer function of a PZT cylindrical phase modulator is delivered. A PZT cylindrical phase modulator is designed, and the numerical simulation is conducted. Results prove that the PZT cylindrical phase modulator can effectively simulate leak acoustic emission signals when the frequency is lower than 25 KHz.

关键词： KHz numerical simulation modulator cylindrical PZT

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Experimental Study on the Piezoelectric Prestage Driver of Electrohydraulic Servo Valves

CHENG Guang-ming, SHEN Chuan-liang, YANG Zhi-gang

《机械工程前沿（英文）》 2006年第1卷第1期页码 56-59 doi: 10.1007/s11465-005-0017-4

摘要：

A piezoelectric actuated prestage driver of hydraulic servo valves for the low-frequency response of electrohydraulic servo valve electromagnetic prestage driver was presented. The new driver was driven by piezoelectric multilayer actuators. The displacement of a piezoelectric multilayer actuator was amplified by a flexure-hinged amplifier based on the principles of triangle amplification. Static and dynamic characteristics were tested on the model machine. The characteristics of good linearity, high resolution, and high-frequency response were approved. The natural frequency reached 1.201 kHz using finite element analysis, and the practice measurement result was 1 kHz.

关键词： flexure-hinged amplifier kHz amplification high-frequency electromagnetic